The Mystery of the Haunted Lighthouse (Three Cousins Detective Club #7)

When Sarah-Jane's father is contracted to restore a run-down lighthouse, the three cousins decide to help out. Then a vandal sabotages their work, and it's up to them to find the culprit.

Long Synopsis:

THREE COUSINS DETECTIVE CLUB #7
It's Sarah-Jane, Timothy, and Titus from the Three Cousins Detective Club! These ,three ten-year-olds are ready to learn about the Fruits of the Spirit while solving more exciting, adventure-filled mysteries!
In The Mystery of the Haunted Lighthouse, Sarah-Jane Cooper and her detective cousins are invited to explore an old lighthouse Mr. Cooper's friend is planning to buy. Sarah-Jane is excited about her first chance to see a real lighthouse, but she can't help thinking it looks a little spooky. Is it just her imagination, or is someone trying to scare them away? It's up to the TCDC to unmask the lighthouse's secret!
Theme: Faithfulness